Gas supply apparatus for ground-effect platforms with multiple air cushions



Feb. 8, 1966 P. GUIENNE 3,233,692

GAS SUPPLY APPARATUS FOR GROUND-EFFECT PLATFORMS WITH MULTIPLE AIR CUSHONS Filed 001". 2l, 1963 B 6/ 1 9U ab 9b 3a 2a 1a 1 b 2b 11b 1a@ l l a 13b 2r:1-/q -10.. 1b- 2b Fig.: 1

INVENTOR Pfl/1L QuIEn/HE B/m' m4190754@ H TTORNEYS United States Patent yO 6 claims. icl. 18o-7) The present invention relates to a modification of the ground effective vehicle described in applicants application Serial No. 165,634 tiled January l1, 1962, and entitled Ground Efect Hovering Platforms and contains a teaching that the stability of such a vehicle is increased by utilizing a plurality of elemental air cushions supplied with air by means as independent as possible. This, for instance, permits reducing the height drop of the platform following passage of an elemental cushion over a ditch, due to the fact that only the lift provided by that particular cushion is reduced by the sudden increase in its leakage section, the lift provided by each of the remaining elemental cushions remaining unaltered.

It is nonetheless desirable to utilize a single compressor for supplying a plurality of cushions,.notably in order to reduce the weight and cost of the machine and facilitate its control. l l v l Y l The present invention enables this to be achieved, using particularly simple means.

The invention consists essentially in disposing, within each branch of a ramilied duct connecting a compressor to a plurality of elemental air cushions, a normally-open hap-valve which immediately closes, at least partly, when a pressure drop in the cushion supplied by that branch and the attendant increase in the rate of ilow that tends to take place entail a modiication of the forces that result from both aerodynamic means and from bias means exerted on said valve.

In accordance with a first embodiment, each elemental valve is supported on a pivot or hinge tangential to its periphery, is urged towards its fully-open position by a spring or the like, and has its stroke limited by two stops, one of which prevents complete closure of the associated duct.

In an alternative embodiment, the valve could be supported on a pivot secant to its outer contour and have a profile such as to bring into play not only the static pressure forces but also the local aerodynamic actions, especially over its leading edge. Such a valve can moreover be statically and/or dynamically balanced by appropriate weights or springs and comprise means for damping its motion.

It will thus easily be appreciated that the invention encompasses operation not only with response of the allor-none type, wherein a hap-valve swivels from an open position in abutment against a stop to a more or less closed position which brings another stop into play, but also with the various forms of gradual operation involving a regulation of the pressure for the associated elemental cushion.

The description which follows with reference to the accompanying drawings, which are filed by way of nonlimitative examples, will give a clear understanding of the various features of the invention and of the manner of carrying them into practice.

Referring to the drawings led herewith:

FIGURE l is a schematic partial vertical section through a platform according to the invention; and

FIGURE 2 shows in corresponding fashion an alternative embodiment involving the use of streamlined and compensated flap-valves covering the entire surface of an elemental cushion.

3,233,692 Patented Feb. 8, 1966 Referring first to FIGURE 1, there is shown thereon a platform with multiple air cushions 1a, 1b, for instance of the type using circular flexible skirts 2a, 2b as described in the applicants prior patent application referred to precedingly. The platform deck 4 supports a number of elemental box-sections 13a, 13b which are extended downwardly by the skirts 2a, 2b and respectively associated to a supply duct 3a, 3b. Said deck also receives a motor 6 for driving an air compressor 7 the outflow from which is delivered into a main duct 5 of which the elemental ducts 3a, 3b constitute ramifications.

Each duct such as 3a comprises a flap-valve 8a. Said valve is pivotally mounted, for instance, on a'pivot 12a tangential to its periphery, is urged into the open position against a stop 11aby a spring 9a, and is prevented from closing fully by a further stop 10a.

In normal operation, the air stream compressed in main duct 5 by compressor 7 divides equally between the several cushions such as 1a, the various elemental skirts such as 2a being positioned at an equal height above practically even ground. The valves 8 are appliedby springs 9 againstthe opening stops 11 with a force sufficient for the possible slight variations in pressure in the various cushions not to entail any change in the positions of said valves.

When a skirt such as Zbtpasses over a ditch, the pressure in the corresponding cushion 1b suddenly diminishes and there is a tendency for an outow markedly greater than normal, from the pressure generator and the cushions, to establish itself from main duct 5 towards the leakage zone. When, however, the pressure drop in cushion 1b reaches a predetermined value, the force resulting from the pressure exerted against the top ot the valve 8b overcomes the tension in the spring 9b and said valve closes. This closing movement is in fact assisted by the aerodynamic forces exerted on the free edge of the valve, so that said valve is urged against the stop 10b. It remains in this position until the cause of the leakage has disappeared, where after the pressure in skirt 1b increases anew up to a value such that spring 9b becomes predominant once more, at which point the valvel opens again and moves against the stop 11b.

The open Vand closed positions of the device hereinbefore described are stable, and it is necessary for .a leak to be provided in the closed position in order to enable the pressure to be restored in the cushion 1b and thereby permit Ireopening of the valve.

Reference is next had to FIGURE 2, which shows an alternative embodiment wherein -the valves 8c, 8d embody progressive operation.

The latter-mentioned valves cover, for example, the entire upper surface of flexible frusto-conicafl skirts 2c, 2d and are fulcrumed about pivots 12C, 12d which are secant to their contours whereby to provide stati-c and dynamic compensation of their weights. Said valves can possibly be restored into their midway positions by one or more springs 9c, 9c .and 9d, 9d and be equipped with dampers 15C, 15d respectively. Lastly but mainly their profiles, more particularly adjacent their leading edges 14e, 14d, could embody a curvature such that the force-s due to the aerodynamic pressures result in an leffective regulation of the pressure of each cushion 1c, 1d about a :selected Amean value. The stops 10c, d, and 11c, d can be made of elastic material and even removed.

Clearly, the head loss through the valves must be as low as possible under steady operating conditions.

A progressively operating valve of the type hereinbefore described is made stable about its positions of equilibrium with respect to the various possible operating conditions of the platform by appropriately determining the stiffness of springs 9c and 9d. The pressure loss introduced by valves such as 8c and 8d during small i transient increases in the ground clearance beneath the corresponding skirts reduces the effective leakage outow under such conditions and leads to an ultimate saving in power and fuel.

It will limmediately be appreciated that it is possible to replace the valves 8a through d described hereabove, the manner of operation of which brings the aerodynamic `forces which they withstand directly into play, and to substitute therefore servo-controlled valves comprising, for instance, control mechanisms sensitive to the pressure, velocity and orientation of the air stream, amplifier stages, and damping and/ or reaction systems.

It goes without saying that the present invention is by no means limited to the specific embodiments described hereinabove, but that its scope includes all such embodiments as can be obtained by recourse to equivalent technical means. In particular, although it has been described with reference to examples relating to platforms having multiple elemental cushions provided with flexible skirts, the invention is generally applicable to all ground-effect platforms utilizing multiple air cushions, irrespective of Whether these cushions are distinct or form part of a partitioned cushion, or Whether they are limited by a :solid wall, a deformable wall, or `at least by a iluid curtain.

What I claim is:

1. In a ground effect vehicle of the type having a pla-tform supported -by a plurality of elemental air cushions, an air supply system for said cushions comprising an a-ir compressing means, a main duct fed with compressed air discharged from said air compressing means, a plurality of elemental ducts connected to said main duct for tapping compressed air therefrom and to respective cushions for supplying compressed air thereto, a separate, independent, pressure sensitive, air flow control valve device in each of said elemental ducts, each said valve device having `a normal open position and being movable to a work position wherein the corresponding ele-mental duct is at least partially closed, said valve device being adapted to be moved towards said work position in response to a drop in pressure of the correspond ing cushion, whereby a pressure drop in any of said elemental air cushions leaves :substantially unaffected the pressure obtained in the other elemental air cushions.

2. A ground effe-ct vehicle according to claim 1 in which said valve device comprises a pivotal flap valve balanced about the pivoting axis thereof. u

3. A ground effect vehicle according to claim 1 in which .said valve device comprises a movable valve member and stroke limiting stops associated with each said valve member.

4. A ground effect vehicle `according to claim 1 in which :said valve device comprises a streamlined Valve member having a rounded leading edge.

5. A ground etect vehicle according to claim 1 in which said valve device comprises a valve member and resilient means associated therewith `for biasing said valve member to normal open position.

6. A ground effect Vehicle according to claim 5 in which valve device comprises further damping means associa-ted with said valve member.

References Cited bythe Examiner FOREIGN PATENTS 236,755 11/1961 Australia.

BENJAMIN HERSH, Primary Examiner.

M. S. SALES, Assistant Examiner. 

1. IN A GROUND EFFECT VEHICLE OF THE TYPE HAVING A PLATFORM SUPPORTED BY A PLURALITY OF ELEMENTAL AIR CUSHIONS, AN AIR SUPPLY SYSTEM FOR SAID CUSHIONS COMPRISING AN AIR COMPRESSING MEANS, A MAIN DUCT FED WITH COMPRESSED AIR DISCHARGED FROM SAID AIR COMPRESSING MEANS, A PLURALITY OF ELEMENTAL DUCTS CONNECTED TO SAID MAIN DUCT FOR TAPPING COMPRESSED AIR THEREFROM AND TO RESPECTIVE CUSHIONS FOR SUPPLYING COMPRESSED AIR THERETO, A SEPARATE, INDEPENDENT, PRESSURE SENSITIVE, AIR FLOW CONTROL VALVE DEVICE IN EACH OF SAID ELEMENTAL DUCTS, EACH SAID VALVE DEVICE HAVING A NORMAL OPEN POSITION AND BEING MOVABLE TO A WORK POSITION WHEREIN THE CORRESPONDING ELEMENTAL DUCT IS AT LEAST PARTIALLY CLOSED, SAID VALVE DEVICE BEING ADAPTED TO BE MOVED TOWARDS SAID WORK POSITION IN RESPONSE TO A DROP IN PRESSURE OF THE CORRESPONDING CUSHION, WHEREBY A PRESSURE DROP IN ANY OF SAID ELEMENTAL AIR CUSHIONS LEAVES SUBSTANTIALLY UNAFFECTED THE PRESSURE OBTAINED IN THE OTHER ELEMENTAL AIR CUSHIONS. 